1. Field
This application relates to the field of carbonated beverage systems, and more particularly to pressure regulators for controlling the pressure at which carbon dioxide is introduced into water in carbonated beverage systems.
2. Description of the Related Art
In the process of mixing carbon dioxide (CO2) gas with water to make carbonated water for post-mix dispensing of soft drinks, the efficiency of dispersion of CO2 gas into water is related to water temperature and pressure. It is desirable to achieve a consistent and repeatable level of CO2 dispersion into the water as this system affects various aspects of a post-mix carbonated beverage such as cup carbonation, foam height, stratification, and taste. Carbonation levels that are too high create excessive foaming in the cup so that when a customer pours a drink, there is a less than optimal amount of drink in the cup after the foam settles. Carbonation levels that are too low cause a “flat” drink, and in many cases low carbonation causes inconsistent or “off” taste drinks.
Currently, there are two carbonation schemes commercially available:
(1) Ambient carbonation—typically utilized with ice-cooled dispensers.
Ice-cooled dispensers have an ice bin with an aluminum cold plate as the bottom of the bin. Syrup and water lines are cast into the aluminum plate. The ice in the ice bin keeps the aluminum plate cold, hence chilling the syrup concentrate and carbonated water passing through the cold plate lines. Historically, this type of dispenser has been designed as a cooling engine and dispense point only. Carbonation has historically been remote from the dispenser and ambient.
(2) Cold carbonation—typically utilized with counter-electric dispensers.
Counter-electric dispensers have a mechanical vapor-compression refrigeration unit with the evaporator coil immersed in a water bath. The vapor-compression refrigeration unit creates an ice bank within the water bath to grow on the evaporator coils. Syrup lines and water lines are routed within the water bath adjacent to the ice bank. Typically, a carbonation tank is also immersed in the water bath which is kept at a constant temperature by virtue of the presence of the adjacent ice.
Cold carbonation is currently the preferred process, because of the fact that the temperature controlled carbonation tank will give consistent carbonation levels because CO2 pressure and water temperature can remain constant and repeatable.
The positive aspect of ambient (room temperature) carbonation is that it is not space constrained. Contrary to cold carbonation, which must currently fit within a counter electric dispenser package envelope, ambient carbonation is accomplished remote from the dispenser and can therefore be easily configured, as necessary, for a particular venue (in terms of peak period usage, total throughput, etc.). However, ambient carbonators typically installed in post-mix soft drink dispensing units are placed in varying locations, which means water temperature and ambient temperatures can vary from the extreme cold of northern states in winter time to the extreme heat of southern states in the summer. In the United States, between the major national soft drink companies and smaller regional soft drink companies, there are in excess of one million post-mix dispenser installations.
The current configuration of a standard ambient carbonator includes a tank, liquid level probe, electric motor driven pump, gas regulator and check valves. The gas regulator is a typical unit including a set screw, spring, diaphragm and valve seat. The regulator accepts input gas in the form of pressurized CO2 and delivers it at a specified pressure to the tank. Typically, the regulated gas setting is somewhere in the range of about 105 psi to 120 psi. The regulator has the capability of one discrete output pressure setting. In order to change the setting, it is necessary for a technician to turn the adjustment screw either in a clockwise or counterclockwise manner which acts to increase or decrease spring compression, hence varying the force on the inlet gas valve seat.
With a discrete pressure regulator and a large network of service technicians, it is ineffective for a large company to effectively vary CO2 pressure specifications based on water temperature because the temperature can change significantly either during the course of a day or also during the span of a year. With 400,000 or more dispenser locations for one large soft drink manufacturer alone, the task of assuring proper carbonation levels by way of discrete pressure settings is financially unfeasible. Therefore, the large soft drink companies elect to simply specify one CO2 pressure which gives the best performance in an average location. This leaves installations with higher than average water temperature and lower than average water temperature slightly out of the optimal CO2 to water ratio specification.
In the post-mix soft drink dispensing industry, it is desirable to vary the CO2 pressure on an ambient carbonation tank so that carbonation level in the dispensed drink is consistent. The level at which CO2 gas will disperse into solution in water is a function of the water temperature and the CO2 gas pressure. Increased water temperature requires increased CO2 pressure to maintain the same level of dissolved CO2 gas in solution. In the soft drink industry, it is generally desirable to have approximately 5.25 volumes of CO2 dissolved into 1 volume of water in the carbonation tank. With CO2 gas pressure set at a constant pressure on the carbonation tank (which is the case with a standard pressure regulator), and considering the ranges of ambient water temperature typically encountered (from about 50° F. to 90° F., for example), it is possible to have a fluctuation of more than 2 volumes of CO2 gas within that ambient water temperature range.
It is important for a soft drink company to achieve consistent performance in its post-mix dispensers. Carbonation level in the dispenser affects cup performance measures such as cup carbonation, foam height and stratification. Consistent quality of post-mix dispensed drinks is key to satisfying customers and gaining repeat business. Previous attempts to achieve such consistency have failed.